Conventionally, a configuration has been known in which, as a bottle formed of a synthetic resin material in the shape of a bottomed cylinder by blow molding, as shown in, for instance, Patent Document 1 below, a bottom wall part of a bottom part includes a grounding part located at an outer circumferential edge thereof, a standing peripheral wall part that connects to the grounding part from a radial inner side of the bottle and extends upward, an annular movable wall part that protrudes from an upper end of the standing peripheral wall part toward the radial inner side of the bottle, and a depression peripheral wall part that extends upward from an inner end of the movable wall part in a radial direction of the bottle, wherein the movable wall part pivots about a connection part with the standing peripheral wall part so as to move the depression peripheral wall part in an upward direction, thereby absorbing decompression in the bottle.